The effect of N,N-dimethylformamide on MAPbI3 nanowires for application in flexible photodetectors

Abstract

Owing to good crystal structure and novel one-dimensional (1D) outer surface, MAPbI₃ nanowires (NWs) show fewer grain boundaries, lower defect density and longer carrier lifetime as compared with their polycrystalline thin films, leading to MAPbI₃ NWs exhibiting higher quantum efficiencies in optoelectronic devices. Herein, by a simple two-step spin-coating method with the addition of various N,N-dimethylformamide (DMF) contents, a PbI₂–DMF adduct is formed; this changes the micro-morphology of MAPbI₃ perovskite from 3 dimensional (3D) nanocubic to 1D NW. Through optimizing the DMF contents, MAPbI₃ NWs with strongest light absorbability and best crystallinity have been obtained (500 μL DMF). In addition, photodetectors (PDs) are assembled with various DMF amounts on glass substrates, and the optimal MAPbI₃ NW PD (500 μL DMF) shows the best performance with on/off ratio greater than 250; the rise and decay times are 12 and 22 ms, respectively. Furthermore, a flexible MAPbI₃ NW PD is assembled, and it shows good sequential and stable response with the on/off ratio of more than 45. Notably, under various bending curvatures and many cycles, the performance of the flexible NW device has only slight degradation. Our results may have great value for the application of flexible MAPbI₃ NW devices in the future.